Humpback Whales: the full behavioural works off Puerto Vallarta, Mexico

What sort of whale watching were we in for we wondered when we landed at Puerto Vallarta on the Pacific Coast of Mexico. We went out into Banderas Bay on two consecutive mornings and found out. It was not the usual sightings of whales ploughing through the sea and then diving ‘tail-up’. This was the full works, especially on the second morning. The Humpbacks (Megaptera novaeangliae) are in the bay from December until March. That population moves north to feed in the Pacific between Russia and North America.

Female Humpbacks and their newly-born young stay in the shallow water at the north end of the bay. Males hang about waiting for the females, with young in tow, to move out of the shallows when coming into their first oestrus post partum. A female may have a pretty permanent male ‘escort’ who may or may not strike it lucky if he can outdo the band of pursuing, barging males.

We saw the males do the full range of their behavioural repertoire from slapping the surface of the water with their fins or tail, flapping water sideways with their tail and breaching. Our breaching count went up rapidly from one (out of the blue before breakfast while anchored off Pitcairn island near the site of the remains of HMS Bounty in 2010) to what must have been more than ten.

There are all sorts of explanations for male Humpbacks breach, from display to shifting skin parasites. My impression—which may be entirely wrong—is that we were witnessing a gigantic aquatic lek within hearing and sight of the females, including those in the shallow water. In other words, my splash is noisier and thus bigger than his so I am the best hope for you to pass on your genes this time round. Oh, and look at how strong my fins are.

We saw one male emerge from the water and snapping its mouth shut as if feeding (see the video below). There have been occasions when the humpbacks have been seen feeding on shoals of small fish in Banderas Bay but in general they live, and the females lactate, using only stored fat and protein. 

We moved to quieter water in highly recommended the Ecotours boat Prince of Whales for the hydrophone to pick up the song of the males. You can hear some of that and see the whales in the video below. After seeing the males flopping back into the water after virtually the whole body had risen out of it, and imagining the effect it would have had on bone and muscle, there was the suggestion from the gentlemen on board that is was no wonder whales wail.

After whales, dolphins, birds nesting on islands in the bay it was off to lunch and birdwatching in the afternoon.